The effects of academic stress on pituitary and adrenal hormones, immunologic function, and overall health will be assessed in a population of first year medical students. This study measures serum levels of ACTH, cortisol, catecholamines, prolactin and growth hormone during periods of academic stress; these levels are correlated to immunologic parameters (NK cell activity, PHA, Con A, macrophage function, and T cell immunity. Health status will be assessed by frequent personal interviews and questionnaires.